小题1:B
小题2:A
小题3:C
小题4:C
文章向我们解释了记忆的原理。
小题1:细节题。根据第二段第2句What makes up this trace is not known.可知B正确。
小题2:推理题。根据第三段第5行Give the person another grocery list. Ask him or her to choose items on the first list from the items that are on only the second list.可知从第2个列表中把第一个列表中的物体挑出来称为再现。
小题3:细节题。根据文章第三段最后一句The difference in the time it takes to relearn the list is thought of as a measure of how much a person has remembered.
小题4:推理题。根据最后一段4,5行For example, a hungry animal quickly learns how to do something if that action gets the animal food.可以推断训练动物做事情最好的方法就是用食物奖励。